1. Field of the Invention
The present invention relates to a method of manufacturing a multi-holed surface plate made of a composite material applied to aircraft engine nacelles, etc. where a lighter weight is required and to a raw element of the composite material to be formed thereby.
2. Description of the Prior Art
In manufacturing a multi-holed surface plate of a composite material, some measure is necessary to provide through-holes on the surface of the plate. A known method of making holes by use of drills or mechanical punches, after a raw forming element of a composite material (hereinafter referred to as "prepreg") is hardened and formed as a product, needs a relatively long working time, is expensive, and is difficult to work.
As a measure to solve this problem, the specification of the Japanese laid-open patent application No. Sho 47(1972)-2131 discloses method of manufacturing a multi-holed reinforced plastic element including a process for hardening plastics contained in a sheet wherein a forming jig, having a back side surface and an open side surface and having a plurality of studs jutted and arranged with a space between each other on the open side surface, each stud being sharpened on its point, is provided and a partially hardened sheet impregnated by reinforced plastics is put on the studs and is so pressed as to be pierced by the studs and then the plastics contained in the sheet is hardened while the sheet is pressed. But in this method also, it is necessary to prepare a special forming jig for each form of product, thus this method was found not necessarily advantageous from the view point of cost of work.